Human factors implications of conceptual design representation in very large databases.

ManagementDoctor of Philosophy (Ph.D.

Understanding in all things : the revelation and transmission of divine insight in the Qumran scrolls and New Testament

SIGLEAvailable from British Library Document Supply Centre- DSC:DXN054088 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Particle deposition in replica healthy and emphysematous alveolar models using computational fluid dynamics

Particle deposition in the pulmonary region of the lung has gained increasing interest in the past years. Of particular interest are nano-sized particles, because they have the potential of crossing the blood-gas barrier and into the capillaries. Many factors contribute to how and where particles deposit, such as lung morphology, breathing conditions, fluid flow characteristics, and alveolar wall movement. These many factors make simulating particle deposition in the alveoli difficult. The experimental in vivo studies have commonly used micron sized particles and there is a lack of data for smaller sized particles. Due to these many factors, deposition in the pulmonary region is not well understood. Furthermore, little attention has been paid to the emphysematous lungs, which have characteristics quite different than the healthy lung. In this work, healthy and emphysematous replica acinus models were created from human lung casts using a 3D reconstruction software package. The models were used for simulating the particle deposition due to diffusion using Fine Particle Model (FPM). The FPM program was validated against an analytical solution using a straight tube, before moving on to predict the deposition in the alveolar models. Two particle sizes, 1 and 3 nm, were used to understand and compare pure diffusion in the lung using concentration contours. Results showed the particle deposition rate (particles/s) to be higher in the emphysemic. However, deposition rate per area (particles/m²s) was found to be higher in the healthy model. The deposition efficiency (% of particles that deposit) of the healthy model was greater than the emphysemic model, consistent with literature. Results were found to be lower than experimental in vivo measurements and whole lung model of local alveolar deposition (particles deposited in alveoli/particles entering alveoli) in comparison to our results in the pulmonary region, showing the importance of including axial diffusion effects. More work must be done experimentally and numerically before an understanding of deposition of particles of this size can be determined

Surface scattering properties estimated from modeling airborne multiple emission angle reflectance data

Here, researchers apply the Hapke function to airborne bidirectional reflectance data collected over three terrestrial surfaces. The objectives of the study were to test the range of natural surfaces that the Hapke model fits and to evaluate model parameters in terms of known surface properties. The data used are multispectral and multiple emission angle data collected during the Geologic Remote Sensing Field Experiment (GRSFE) over a mud-cracked playa, an artificially roughened playa, and a basalt cobble strewn playa at Lunar Lake Playa in Nevada. Airborne remote sensing data and associated field measurements were acquired at the same time. The airborne data were acquired by the Advanced Solid State Array Spectroradiometer (ASAS) instrument, a 29-spectral band imaging system. ASAS reflectance data for a cobble-strewn surface and an artificially rough playa surface on Lunar Lake Playa can be explained with the Hanke model. The cobble and rough playa sites are distinguishable by a single scattering albedo, which is controlled by material composition; by the roughness parameter, which appears to be controlled by the surface texture and particle size; and the symmetry factor of the single particle phase function, which is controlled by particle size and shape. A smooth playa surface consisting of compacted, fine-grained particles has reflectance variations that are also distinct from either the cobble site or rough playa site. The smooth playa appears to behave more like a Lambertian surface that cannot be modeled with the Hapke function

Magnetic imaging of 3D artificial spin-ice structures

This thesis is a meticulous journey into the realm of three-dimensional Artificial Spin Ices (ASI), pushing the boundaries of exploration beyond the familiar territories of two dimensions. Employing methodologies like two-photon lithography and thermal evaporation, it navigates the intricate landscape of diamond-bond lattice geometries, unveiling emergent behaviours such as monopole propagation. Section 3 meticulously charts the ASI structure's three-dimensional phase diagram, comparing predictive Monte Carlo simulations with experimental observations. The diversity of predicted phases, from double-charged monopole crystals to conventional spin ice, is scrutinized through magnetic force microscopy (MFM), revealing new vertex types and providing data for comparisons with simulations. Discrepancies between anticipated and observed ground states are attributed to an effective chemical potential (μ^*) and limitations in the deterministic demagnetisation protocol. Ferromagnetic dominance on the upper surface layer and a higher μ^* for monopole formation impede the anticipated double-charged crystal, except in localized disorder regions. Recommendations for modifying the topography of the surface layer are proposed to realize this state. Delving deeper into the system, x-ray magnetic circular dichroism (XMCD) is suggested to probe layers with a 1-unit cell thickness, expanding comprehension. Future plans involve transforming the 3D ASI into a thermally dynamic system, challenging for measurement techniques like MFM due to state perturbation and extended times. Section 4 delves into synchrotron-based techniques, notably transmission X-ray microscopy with XMCD, affirming permalloy nanowire structures' crescent-shaped cross-section. Refinements in fabrication methods, despite revealing oxidization of the magnetic coating, offer nuanced insights into magnetic behaviours within the 3D ASI. XMCD measurements hint at weak signals, particularly in SL2, suggesting the need for further fabrication refinements and envisioning polymer-free magnetic nanowire-based 3D ASI designs for future exploration. In a meticulous journey through ASI's three-dimensional landscapes, this thesis unearths complexities, proposes modifications, and sets the stage for deeper explorations into emergent phenomena

High-Rate Data-Capture for an Airborne Lidar System

A high-rate data system was required to capture the data for an airborne lidar system. A data system was developed that achieved up to 22 million (64-bit) events per second sustained data rate (1408 million bits per second), as well as short bursts (less than 4 s) at higher rates. All hardware used for the system was off the shelf, but carefully selected to achieve these rates. The system was used to capture laser fire, single-photon detection, and GPS data for the Slope Imaging Multi-polarization Photo-counting Lidar (SIMPL). However, the system has applications for other laser altimeter systems (waveform-recording), mass spectroscopy, xray radiometry imaging, high-background- rate ranging lidar, and other similar areas where very high-speed data capture is needed. The data capture software was used for the SIMPL instrument that employs a micropulse, single-photon ranging measurement approach and has 16 data channels. The detected single photons are from two sources those reflected from the target and solar background photons. The instrument is non-gated, so background photons are acquired for a range window of 13 km and can comprise many times the number of target photons. The highest background rate occurs when the atmosphere is clear, the Sun is high, and the target is a highly reflective surface such as snow. Under these conditions, the total data rate for the 16 channels combined is expected to be approximately 22 million events per second. For each photon detection event, the data capture software reads the relative time of receipt, with respect to a one-per-second absolute time pulse from a GPS receiver, from an event timer card with 0.1-ns precision, and records that information to a RAID (Redundant Array of Independent Disks) storage device. The relative time of laser pulse firings must also be read and recorded with the same precision. Each of the four event timer cards handles the throughput from four of the channels. For each detection event, a flag is recorded that indicates the source channel. To accommodate the expected maximum count rate and also handle the other extreme of very low rates occurring during nighttime operations, the software requests a set amount of data from each of the event timer cards and buffers the data. The software notes if any of the cards did not return all the data requested and then accommodates that lower rate. The data is buffered to minimize the I/O overhead of writing the data to storage. Care was taken to optimize the reads from the cards, the speed of the I/O bus, and RAID configuration

Addressing common sources of bias in studies of new-onset type 2 diabetes following COVID that use electronic health record data

Observational studies based on cohorts built from electronic health records (EHR) form the backbone of our current understanding of the risk of new-onset diabetes following COVID. EHR-based research is a powerful tool for medical research but is subject to multiple sources of bias. In this viewpoint, we define key sources of bias that threaten the validity of EHR-based research on this topic (namely misclassification, selection, surveillance, immortal time, and confounding biases), describe their implications, and suggest best practices to avoid them in the context of COVID-diabetes research

In Vitro Bacterial Contamination of Amniotic Fluid: Effects on Fluorescence Polarization Lung Maturity Testing

Objective: We sought to determine the effect of bacteria on fluorescence polarization (FPOL) testing of amniotic fluid

Mapping the Galactic Halo. V. Sgr dSph Tidal Debris 60 degrees from the Main Body

As part of the Spaghetti Project Survey (SPS) we have detected a concentration of giant stars well above expectations for a smooth halo model. The position (l~350, b~50) and distance (~50 kpc) of this concentration match those of the Northern over-density detected by SDSS (Yanny et al. 2000, Ivezic et al. 2000). We find additional evidence for structure at ~80 kpc in the same direction. We present radial velocities for many of these stars, including the first published results from the 6.5m Magellan telescope. The radial velocities for stars in these structures are in excellent agreement with models of the dynamical evolution of the Sgr dwarf tidal debris, whose center is 60 degrees away. The metallicity of stars in these streams is lower than that of the main body of the Sgr dwarf, which may indicate a radial metallicity gradient prior to disruption.Comment: 10 pages, 3 figures accepted in Astrophysical Journal Letter